physical science mr. barry. series circuits have one loop through which current can flow
TRANSCRIPT
Physical Science
Mr. Barry
Series circuits have one loop through which current can flow
Parallel Circuits: have two or more branches through which current can flow
In a parallel circuit: Voltage difference is the same across all
branchesMore current flows through branches with
lower resistanceConnecting wires have the most current flow
In your house: Parallel circuits with circuit breakers
Circuit breakers have a main breaker in series with many parallel circuits. The parallel circuits each have circuit breakers. When the wires overheat, the circuit breaker switches off the current.
Look at figure 18 on page 209
Electric Power: The rate at which electric energy is converted into another form of energy
P = IVPower is measured in Watts, Current in
Amperes, Voltage in VoltsAppliances with heating elements usually use
more electric power
A 9 Volt battery powers a digital clock. The current through the clock is 6.67 Amps. How much power does the clock use?
P = IVP = (6.67)(9)P = 60.0 W
A light bulb uses 60 Watts of Power. It is plugged into a 120 Volt electrical outlet. What current flows through the bulb?
P = IVI = P/V
I = (60)/(120)I = 0.5 A
Electric Energy: The electric company charges you for the electrical energy you use, which depends on the amount of power and the length of time it is used
E = PtElectrical energy is measured in kilowatt
hours (kWh), Power in kilowatts, and time in hours
A digital clock uses 60 Watts of power for 24 hours. How much electrical energy is used by the clock in one day?
E = PtP = 0.060 kW
E = (0.060) (24)E = 1.44 kWh
The electrical energy used by a clock in one day is 1.44 kWh. The power company charges $0.09 per kWh. How much does it cost to run the clock for a 30-day month?
Cost = E x RateE = (1.44/day)(30days)E = 43.2 kWh all month
E x Rate(43.2)($0.09)
= $3.88
The electrical power used by a light bulb is 60 Watts. The bulb is on for approximately 7 hours each day. How much electrical energy does the light bulb use per day?
E = PtP = 0.060 kWE = (0.060) (7)E = 0.42 kWh
The electrical energy used by the bulb each day is 0.42 kWh. The electrical company charges $0.09 per kWh. What is the cost per year? (for this year)
Cost = E x RateE = (0.42/day)(366days)E = 153.72 kWh all year
E x Rate(153.72)($0.09)
= $13.83